Aerovee idle issue

[jwd3ca]

Greetings...

Currently in flight testing for re-engining my Sonex #325 from Jab 3300 to AeroVee. Although the engine runs well at idle (900-1000), I'm having issues getting it to idle down while running. Like on final. If I 'blip' the throttle, it will usually idle down, but that's a kludge I'd rather not have to deal with. It seems to me that the flexible twisted wire cable may be the issue, not forcing the slide down the way the solid wire would. I flew several hundred hours with my 3300/AeroCarb with solid wire, never had an idle issue. Thinking about going back to solid wire. Thoughts?

[ScottM-Sonex1629]

I believe your correct about the braided throttle cable as the issue. My AeroVee and aeroinjector acts the same way. I actually prefer that it doesn't Idle down below 1100 rpm on final. After taxiing back to the hangar I can pull the throttle back a little firmer and it will idle around 850-900 rpm.

Noticed your other thread about the static rpm concerns. What prop are you using? How many hours do you have on the AeroVee now? Curious why you switched from a 3300 down to the AeroVee?

[jwd3ca]

Prince P-Tip 54/44, about 10 hours so far, optimistic about seeing 3080 static recently. Haven't yet flown or done a climb test since seeing this...

[ScottM-Sonex1629]

Ok good info. Your using the same prop combo that I have. Definitely get the gear fairings and wheel pants on the plane if you don't have those installed. On my recent flight I was seeing 3080-3100 RPm during climb out at 75 mph, solo, with a 8-10 mph headwind and was climbing out at 850-900 FPM. The OAT was 38 deg F. If you can get 3100-3250 RPM static that's about normal with this propellor.

Have you confirmed the secondary ignition timing setting? This really can only be done accurately during test flights (follow the procedure in the AeroVee manual).

[jwd3ca]

Ignition timing seems to be spot on, no RPM difference between them at WOT. Got gear leg fairings but no wheel pants on larger-than-stock tires. Is your 850-900 FPM at full gross? I'd be thrilled to see that! Seeing like 3-400 now. BTW, I 'stole' the 3300 out of my Sonex #325 to power my latest build- Zenith CH750, and it is performing awesome. (As it did in the Sonex. )

[ScottM-Sonex1629]

That rate of climb was SOLO, with cool outside air. Density altitude was 870', almost 300' below my field elevations! I flew two weeks ago for the first time at gross weight (close to 1150 lbs) and was seeing climb rates in the 300-400 FPM range with my son aboard.

Here's a few pictures from my recent flight to show you the numbers...



After leveling off I powered back to a speed cruise setting to see what the cold air would do for the performance...

[jwd3ca]

To properly pass my climb test I need to see approximately 500 fpm at full gross (1100).i

[MichaelFarley56]

To properly pass my climb test I need to see approximately 500 fpm at full gross (1100).i

If you want that level of performance you'll certainly need every fairing you have installed, test on a cold day, and probably limit your maximum takeoff weight to 1000-1050. Most AeroVee Sonexes climb around 400 fpm out of low elevation airports at takeoff weights of 1100 lbs; maybe not stellar, but completely adequate for most people. Just my two cents of course!

[jwd3ca]

I may have overstated the 500 fpm on re-calculating the minimum climb based on Transport Canada charts. Using today's pressure altitude (900') and ambient temp (14C=57F), I'm required to climb 1100' in 3 minutes. 366 fpm. Whatever take-off weight can achieve this will be the maximum permissible weight listed on my C of A.

[n982sx]

You won't have any issue getting your climb performance with those temperature and density altitude numbers.

The worst performance I have ever gotten is 300 fpm at a gross weight of 1150 and temps in the low 90s from a field elevation of about 600'. I don't remember the density altitude when I did my high gross weight testing but it was certainly higher than 600' and very hot.